It has been proposed that the design of robots might benefit from interactions that are similar to caregiver-child interactions, which is tailored to children's respective capacities to a high degree. However, so far little is known about how people adapt their tutoring behaviour to robots and whether robots can evoke input that is similar to child-directed interaction. The paper presents detailed analyses of speakers' linguistic behaviour and non-linguistic behaviour, such as action demonstration, in two comparable situations: In one experiment, parents described and explained to their nonverbal infants the use of certain everyday objects; in the other experiment, participants tutored a simulated robot on the same objects. The results, which show considerable differences between the two situations on almost all measures, are discussed in the light of the computer-as-social-actor paradigm and the register hypothesis. Keywords: child-directed speech (CDS); motherese; robotese; motionese; register theory; social communication; human-robot interaction (HRI); computers-as-social-actors; mindless transfer